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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

2409 results found.

  1. GRB 250329B: SVOM detection of a faint transient
  2. GRB 250329A: Swift-XRT afterglow detection
  3. GRB 250328A: SVOM/VT optical observation
  4. GRB 250329A: Fading optical counterpart detection by LCO.
  5. GRB 250328A: SVOM/C-GFT optical upper limit
  6. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  7. GRB 250328A: VLT/HAWK-I near-infrared afterglow candidate
  8. GRB 250329A: VLT/X-shooter redshift z = 2.921
  9. GRB 250329A: SVOM/VT optical counterpart confirmation
  10. GRB 250329A: SVOM detection of a burst
  11. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  12. GRB 250327B: MASTER detection of OT rebrightening
  13. GRB 250327B: LCO optical counterpart detection
  14. GRB 250328A: GWAC-F50A optical upper limit
  15. GRB 250328A: SVOM detection of a burst
  16. GRB 250327B: OHP/T193 spectroscopic observations and redshift confirmation
  17. GRB 250327B: further optical observations by LCOGT
  18. GRB 250327A: SVOM/VT upper limits on the XRT position
  19. GRB 250327B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  20. GRB 250327B: Las Cumbres optical counterpart detection
  21. GRB 250327B: Swift-XRT detection of the X-ray afterglow
  22. GRB 250327B: 1.6m Mephisto optical observations
  23. GRB 250327B: NOT spectroscopic redshift z = 3.035
  24. GRB 250327B: GOTO optical counterpart detection
  25. GRB 250327B: SVOM/VT optically bright counterpart
  26. GRB 250327B: SAO RAS optical candidate
  27. GRB 250327B: SVOM detection of a burst
  28. GRB 250327A: J-band observations with WINTER
  29. GRB 250327A: SVOM/VT optical candidate
  30. GRB 250321B: Swift-XRT observations
  31. SVOM/sb25032302: SVOM detection of a long X-ray transient
  32. GRB 250321B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  33. GRB 250225B: GECAM-A detection
  34. GRB 250321B: Swift ToO observations
  35. GRB 250320B: NuSTAR detection of the prompt emission from two broad bursts and preliminary analysis
  36. GRB 250320B: Fermi GBM Observation
  37. GRB 250320B: Fermi-LAT detection
  38. GRB 250321B: SVOM detection of a sub-threshold transient event
  39. EP250321a: SVOM/VT optical observation
  40. GRB 250320B: SVOM/GRM observation of a long burst
  41. GRB 250314A: Keck/NIRC2 J-band upper limit
  42. GRB 250313A: GRBAlpha detection
  43. GRB 250317B: SVOM/COLIBRI (F-GFT) follow-up observations
  44. GRB 250317C: SVOM/GRM observation of a long burst
  45. GRB 250317B: Leavitt Observatory optical upper limit
  46. GRB 250317B: GTC/OSIRIS+ spectroscopic redshift z=3.44
  47. GRB 250317B: REM optical/NIR observations
  48. GRB 250317B: Swift-XRT observations
  49. GRB 250314A: REM optical/NIR upper limits
  50. EP 250317B: Fading optical counterpart detection by LCO
  51. GRB 250317B: LCO detection of the fading optical afterglow
  52. GRB 250317B: refined SVOM/MXT analysis
  53. GRB 250317B: SVOM/VT detection of an optical candidate from VHF data
  54. GRB 250317B: SVOM/F-GFT (COLIBRÍ) Detection of a Fading Optical Counterpart
  55. GRB 250317B: SVOM detection of a burst / correction to GRB name of GCN 39752
  56. GRB 250317B: SVOM detection of a burst
  57. GRB 250314A: SVOM/GRM analysis
  58. GRB 250314A: GTC z-band upper limit and updated photo-z ~ 7.27
  59. GRB 250314A: EP-FXT afterglow detection
  60. GRB 250314A: Swift/UVOT Upper Limits
  61. GRB 250314A: Swift XRT Detection
  62. GRB 250314A: VLT/X-shooter dropout, redshift z ~ 7.3
  63. SVOM/MXT upper limit on GRB 250314A
  64. GRB 250314A: SVOM/VT upper limit
  65. GRB 250314A: NOT near-infrared candidate counterpart
  66. GRB 250313A: Fermi GBM Detection
  67. GRB 250313A: CALET Gamma-Ray Burst Monitor detection
  68. GRB250314A: SVOM/VT lack of bright optical candidate from VHF data
  69. Konus-Wind detection of GRB 250313A
  70. Konus-Wind detection of GRB 250308A
  71. GRB 250314A: SVOM detection of a burst
  72. GRB 250313B: SVOM/GRM observation of a soft bright short burst
  73. GRB 250313A: SVOM/GRM observation of a bright long burst
  74. EP250304a: SVOM/VT optical observation
  75. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  76. GRB 250308A: CALET Gamma-Ray Burst Monitor detection
  77. GRB 250311B: SVOM detection of a burst
  78. GRB 250309B: SVOM/VT optical observation
  79. IPN triangulation of GRB 250308A (short)
  80. GRB 250308A: SVOM/GRM detection of QPO in the tail emission
  81. GRB 250308A: SVOM/GRM observation of a bright short burst
  82. GRB 250305A: AstroSat CZTI detection
  83. GRB 250305A: SVOM/GRM observation of a burst
  84. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  85. Konus-Wind detection of GRB 250222A
  86. IPN triangulation of GRB 250222A
  87. EP250302a: SVOM/VT optical observation
  88. EP250302a: Xinglong F60B optical observation
  89. EP250302a: SVOM/C-GFT optical observations
  90. GRB 250225B: EIRSAT-1 GMOD Detection
  91. GRB 250226A: Fermi GBM Observation
  92. GRB 250225B: INTEGRAL SPI-ACS detection
  93. EP250226a / GRB 250226A: SVOM/VT optical observations
  94. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  95. GRB 250225B: REM NIR upper limits
  96. Konus-Wind detection of GRB 250225B
  97. GRB 250225B: SVOM/GRM observation of a long burst
  98. GRB 250214A: SVOM/GRM observation
  99. GRB 250223C: SVOM/GRM observation of a long burst
  100. GRB 250219A: EP-FXT afterglow detection

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